Returning earth efficiently and quickly into an excavation from which the earth has been removed has been a problem of long standing in the earth moving field. Many machines have been designed to handle this problem, the various machines solving the problem with varying degrees of success. A particularly troublesome problem, which has not been successfully solved, is returning removed earth back into a long ditch into which an oil or gas transmitting pipeline has been laid. In this application, using modern pipe laying methods, a long cleanly cut ditch is excavated across the countryside, after which the pipeline is laid in the ditch and is subsequently buried with the earth that has been removed from the ditch. When the ditch for the pipeline is being excavated, the removed earth is piled in a relatively neat elongated ridge alongside the ditch. If conventional earth moving equipment is used, it is difficult, without encountering considerable waste motion and time, to replace the removed earth in the ditch. An endless track vehicle commonly known as a dozer with an angled blade, is sometimes used, but the earth has a habit of piling up and spilling over both sides of the blades with the result that at least two passes with the dozer blade, and frequently more, must be made in order to fill the ditch. A dozer blade also has a tendency to compact the earth and move boulders, and earth lumps to the front, which when they drop into the ditch can cause damage to the protective coating on the pipe lying at the bottom of the ditch. Earth moving augers are also used for moving earth back into ditches, but they are less than completely successful for similar reasons.
In pipeline laying situations, it is sometimes necessary to lay a crude oil carrying pipeline in a right-of-way that is parallel to a natural gas carrying pipeline that is an adjacent right-of-way. In this situation it is important that no earth excavated for the second pipeline ditch is deposited on the right-of-way for the first laid pipeline, because the weight of heavy earth moving equipment on the ground above the first laid pipeline can cause damage to the first laid pipeline. It is difficult for conventional dozers and the like to deal with this problem because earth always tends to spill by both sides of the dozer blade.
Another problem is stripping top soil from a right-of-way. Often this must be done in very restricted widths, and the soil must not spill over onto the land adjoining the right-of-way. This is an increasingly common problem, for example, in subdivision areas, easements over densely occupied land, and the like. An earth moving contractor can expose himself to a law suit by spilling earth onto privately owned land, particularly if damage is caused in removing the earth from the land.
Another problem that has arisen in recent years is that concern with the ecology has become prevalent, and authorities in response to this concern, whenever pipelines and the like are installed across the country, have required among other things that valuable excavated top soil be kept on the surface and returned to its approximate original location in fundamentally the same state as when it was removed. Fulfilling this requirement is time consuming and often represents difficult work for conventional earth moving equipment, because considerable time and numerous traverses of the equipment are required, all of which translate into considerable expense.